Gas turbine with pyrometer

ABSTRACT

A gas turbine with at least one stationary stator blade and at least one rotor blade that can be rotated during operation is provided. The gas turbine has at least one optical waveguide embedded into a first rotor blade. The optical waveguide is oriented such that thermal radiation of a region of the first stator blade can be detected by the optical waveguide. An analyzing device is designed to analyze the thermal radiation and to ascertain the temperature of the region of the first stator blade, the temperature being ascertainable along a path from which the radiation is emitted during the rotation of the first rotor blade.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is the U.S. National Stage of International ApplicationNo. PCT/EP2012/060209 filed May 31, 2012, and claims the benefitthereof. The International Application claims the benefit of GermanApplication No. DE 102011077908.6 filed Jun. 21, 2011. All of theapplications are incorporated by reference herein in their entirety.

FIELD OF INVENTION

The invention relates to a gas turbine having at least one stationarystator blade and at least one rotor blade which can be rotated duringoperation.

BACKGROUND OF INVENTION

Work on the efficiency of modern gas turbines never stops. An increasedefficiency can always be achieved in this case by an increased operatingtemperature. Here, the operating temperature continuously approaches thelimits of the thermostability of the blade materials being used. Inorder to avoid overloading, the temperature of individual components ofa gas turbine is monitored. By way of example, pyrometers are used forthis purpose which detect the thermal radiation of individualcomponents, lead it to a detector and evaluate it there, thusdetermining the temperature of the component. A multiplicity oftemperature measurement points and temperature measuring devices areused so as to be able to measure local variations in the temperature.

Owing to their fixed position relative to the burners, the stationaryblades, called stator blades, have larger inhomogeneities in thetemperature distribution than the rotor blades, which rotate duringoperation. The temperature distribution in the stator blades istherefore of great interest. To date, the temperature of the statorblades has been measured in a punctiform manner with the aid of alimited number of stationary thermoelements.

SUMMARY OF INVENTION

It is an object of the present invention to specify a gas turbine in thecase of which the temperature distribution in the stator blades can bemore accurately detected.

This object is achieved by a gas turbine as described herein.

The gas turbine according to an embodiment comprises at least onestationary stator blade and at least one rotor blade which can berotated during operation. Also present is at least one opticalwaveguide, which is embedded in a first rotor blade and is aligned suchthat thermal radiation of a first stator blade can be detected by theoptical waveguide.

The gas turbine according to an embodiment also comprises an evaluationdevice for evaluating thermal radiation. The evaluation device isconfigured to determine the temperature of at least the first statorblade, it being possible to determine the temperature along a path fromwhich the thermal radiation is detected in the course of the rotation ofthe first rotor blade and thus of the optical waveguide.

The region of the stator blade whose thermal radiation is recorded is inthis case a function of the optical waveguide and of the distance of theoptical waveguide end from the stator blade.

Differently put, in an embodiment the pyrometer, which is represented bythe optical waveguide, rotates together with a rotor blade and isdirected toward a stator blade. The temperature of the stator blade cantherefore advantageously no longer be determined only at fixed points atwhich thermal elements are provided, but at any point on a circulartrack which results from the movement of the rotor blade relative to thestator blade. The temperature distribution of the stator blade can thusbe detected much more accurately than previously.

In one refinement and development of an embodiment, the first rotorblade comprises a photodetector for converting the thermal radiationinto electrical signals. In this case, the photodetector is expedientlycoupled to the optical waveguide in order to be able to detect thethermal radiation, which comes from the first stator blade, afterpassage through the optical waveguide. The photodetector can, forexample, be fed in this case by wireless energy transfer. Alternatively,the photodetector can be fed by means of a battery. The pyrometer isadvantageously implemented thereby substantially in the rotor bladeitself. The data determined can then be recorded and/or passed on bytelemetry or by a corotating data plotter.

In a further refinement and development of an embodiment, the opticalwaveguide is guided into the shaft of the first rotor blade andterminates there. It is possible through this configuration for therecorded thermal radiation to be output in the direction of stationaryparts of the gas turbine. Said radiation can be more simply recorded andfurther processed there. It is then advantageous when the end of theoptical waveguide in the shaft is provided with a collimator. Inaccordance with an advantageous refinement of an embodiment, it ispossible hereby for the emerging thermal radiation to be emitted in anaxial parallel beam. This enables the radiation to be recorded as far aspossible without attenuation after traversing a short air gap.

In an advantageous refinement of an embodiment, the radiation comingfrom the collimator is detected with the aid of a detection device,wherein the reception range of the detection device is formed over solarge an area that substantially all radiation coming from thecollimator can be detected. The comparatively large area of theconfiguration of the detection device enables the thermal radiation tobe detected and further processed without attenuation. The accuracy ofthe measurement is thereby ensured.

In order to separate the detection device from the ambient light, andthus to reduce or to avoid a recording of the ambient light, it isadvantageous to provide a cover or sleeve in the region of the detectiondevice.

In one refinement of an embodiment, the detection device is an opticalwaveguide, in particular an optical waveguide with a comparatively largecross section, or a bundle of optical waveguides. The opticalwaveguide/waveguides serves/serve to pass on radiation in a stationarypart of the gas turbine to a photodetector. The use of opticalwaveguides as detection device enables the detector to be implemented ina thermally less stressed region of the gas turbine.

Alternatively, the detection device can also directly be thephotodetector. Said photodetector is then preferably provided with asufficiently large detector area in order, in turn, to provide as far aspossible for attenuation-free recording of the thermal radiation.

In one advantageous refinement and development of an embodiment, a lenscollimator is provided in the region of the end of the optical waveguidereaching the first stator blade. Alternatively, the optical waveguidecan be configured in a tapered fashion at its appropriate end. It isthereby possible to control the region of the surface of the statorblade from which thermal radiation is recorded.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred, but in no way limiting exemplary embodiments of the inventionare now explained in more detail with the aid of the figures of thedrawing, in which the features are schematized. In the drawing:

FIG. 1 shows an arrangement of the rotating pyrometer in principle, and

FIG. 2 shows variants of the receiving collimator on the rotor blade.

DETAILED DESCRIPTION OF INVENTION

FIG. 1 shows a section of a gas turbine 10. This means that only partsof the components are schematized. The gas turbine 10 comprises a rotorblade 11 and stator blades 12. The rotor blade 11 is arranged rotatablyon a shaft 17. The stator blades 12 are arranged fixed to the housingand do not rotate during operation.

A glass fiber 13 is embedded in the rotor blade 11. It runs therein froman end situated on the surface of the rotor blade 11 into the shaft 17.The end situated on the surface of the rotor blade 11 points in thedirection of the stator blades 12. Provided at the end of the opticalwaveguide 13 there is a lens collimator 14.

The other end of the glass fiber 13 lies on a surface of the shaft 17.The glass fiber 13 terminates there with a second collimator 18. Thesecond collimator 18 is configured in this case such that the outputradiation emerges in an axial parallel beam. The radiation thus outputenters a photodetector 20 whose receiving surface has a large area bycomparison with the cross section of the glass fiber 13.

FIG. 2 shows variants of the termination of the glass fiber 13, whichpoints in the direction of the stator blades 12. Thus, as indicated inthis exemplary embodiment, the glass fiber 13 can be terminated with thelens collimator 14. A further possibility and alternative consists interminating the glass fiber 13 in such a way that the glass fiber has atapered end 22. A further alternative consists in using a glass fiber 13of lower aperture. Said end 21 of the glass fiber 13 then has no specialconfiguration.

During operational running, a region 16 of a stator blade 12 emitsthermal radiation in accordance with its temperature. In this case, theregion 16 is small by comparison with the size of the stator blade 12.The thermal radiation enters the glass fiber 13 via the lens collimator14. It is led there up to its other end and enters the photodetector 20through the second collimator 18 and the following air gap. Theelectrical signals initiated by the radiation 19 are evaluated, and thetemperature of the region 16 is thereby determined.

The rotor blade 11 rotates during operational running. The glass fiber13 necessarily co-rotates in this case. The region 16 of the statorblade 12 that is under consideration thereby travels around the shaft 17on a circular track. Since said movement is relatively quick, it ispossible at practically any time to consider the temperature of eachregion 16 of the stator blade 12 which lies on the circular track. Allthat this requires is to wait until the rotor blade 11 has passed onceover the desired region 16. The temporal resolution of the evaluation inthis case determines which angular section of the circular path willultimately be regarded as region 16.

1. A gas turbine, comprising at least one stationary stator blade and atleast one rotor blade which can be rotated during operation, at leastone optical waveguide, which is embedded in a first rotor blade and isaligned such that thermal radiation of a region of the first statorblade can be detected by the optical waveguide, and an evaluation devicefor evaluating the thermal radiation, which is configured to determinethe temperature of the region of the first stator blade, it beingpossible to determine the temperature along a path from which thethermal radiation emanates in the course of the rotation of the firstrotor blade.
 2. The gas turbine as claimed in claim 1, wherein the firstrotor blade comprises a photodetector for converting the thermalradiation into electrical signals.
 3. The gas turbine as claimed inclaim 2, wherein the photodetector is fed by wireless energy transfer.4. The gas turbine as claimed in claim 1, wherein the optical waveguideis guided into the shaft of the first rotor blade and terminates there.5. The gas turbine as claimed in claim 4, wherein the end of the opticalwaveguide in the shaft is provided with a collimator.
 6. The gas turbineas claimed in claim 5, wherein the collimator is configured to emit theemerging radiation in an axial parallel beam.
 7. The gas turbine asclaimed in claim 4, wherein the radiation coming from the collimator isdetected with the aid of a detection device, wherein the reception rangeof the detection device is formed over so large an area thatsubstantially all radiation coming from the collimator can be detected.8. The gas turbine as claimed in claim 7, wherein the detection devicehas a cover or sleeve to prevent ambient light from scattering in. 9.The gas turbine as claimed in claim 7, wherein the detection device isan optical waveguide or a bundle of optical waveguides for passing onthe radiation to a photodetector.
 10. The gas turbine as claimed inclaim 7, wherein the detection device is a photodetector.
 11. The gasturbine as claimed in claim 1, wherein a lens collimator is provided inthe region of the end of the optical waveguide pointing toward the firststator blade.
 12. The gas turbine as claimed in claim 1, wherein theoptical waveguide is tapered at its end.